Every Earth Day, I try to take a moment to reflect on how cool our planet is. Between playing in extreme weather events and dancing over unbelievable mountain terrain, skiing is an amazing way to appreciate the Earth and the qualities that make it special. With the recent successful return of the crew of Artemis II and eventually a possible return to the moon, I’ve been pondering if there might be other places in the solar system that humans may be able to ski, and if they are as rad as anything on Earth.
Naturally, the first place to look would be the moon, both because of its closeness and because of the starring role it has played in several moonlit skiing nights over the years. A couple of years ago, SnowBrains pondered this very question, and perhaps Candide would find the idea of skiing moondust appealing, but having to wait for 150,000 years for my tracks to fill in probably cuts into the ski quality at least a little bit. I’m more inclined to search elsewhere in the solar system.
Mars is home to some enormous mountains, the largest being Olympus Mons, which tops out at over 70,000 feet above the Martian surface. Seems promising. However, the Martian atmosphere is mostly carbon dioxide, and while there can be strong Martian winds, there is practically no precipitation of any kind. The surface of Mars is at an average temperature of -60 °C, so snowmaking on Mars to fill in a long, gentle ribbon of death on the shoulder of the crater, or a steep descent down the crater wall may seem tempting, but the Martian winds likely carry all the ice crystals far, far away. Not to mention the lack of water supply.
Mars has two polar ice caps, which are actually made of water ice and dry ice, or solidified carbon dioxide. Some of the craters near the poles are full of water ice, but it’s worth mentioning that at extremely low temperatures, like Martian temperatures, water ice can become harder than aluminum and almost as hard as iron, so carving turns on old Martian ice will be harder than the iciest day any New Englander can remember. Much like the Earth’s ice caps, the Martian ice caps grow and shrink with the seasons, through deposition and sublimation of dry ice. At its peak, this dry snowpack is up to a meter deep. I’ve had a lot of fun skiing far less than a meter of new snow, but the problem is that all of the tall mountains of Mars are located in the equatorial region, far, far away from the ice caps. Alas, it seems we will have to journey further out in the solar system in search of powder skiing.
To make a really good extraterrestrial ski run, we need topography, a slippery surface, and snow, or some form of snow. Several moons of Jupiter, namely Europa, Ganymede, and Callisto, have icy surfaces, but lack both topography and weather producing any kind of precipitation. The same goes for Enceladus, Dione, Tethys, and Rhea, Saturn’s icy moons. Titan, Saturn’s largest moon, holds some promise. The atmosphere is mostly nitrogen, but contains copious amounts of methane and is thick enough to support weather patterns we might recognize on Earth. Drizzling, foggy methane clouds are ubiquitous, and occasionally full on rainstorms cause methane rivers to flow into methane lakes. In terms of mountain ranges, Titan does not disappoint. The Mithrim Montes, Titan’s tallest peaks, top out at over 10,000 feet, and radar images from the Cassini spacecraft have indicated methane snow may cover the tops of these peaks. Little is known about how deep these methane snowpacks may be, and a milimeter or less could be enough to produce the bright reflections observed in the images. It would be a shame to travel all the way to Titan with special skis waxed with graphene to deal with sticky methane snow, only to find a methane rainstorm.
Pluto contains mountains of ice similar to those on Titan, but perhaps on an even more impressive scale. The tallest peaks are in the Tenzing Montes, and top out at nearly 20,000 feet. Weather patterns in Pluto’s thin atmosphere seem to produce nitrogen or methane snow in these mountains and across the Sputnik Planitia, so much so that massive glaciers of nitrogen ice, similar to Earth’s own glaciers, flow across the surface. So, what are we waiting for? Time to rig up an A-Star to work in one millionth the pressure of Earth or rig up a rope tow to run off an old lunar rover tire and get to the shredding? Since Pluto is a really long way to go, I’d want to be pretty confident that the skiing will be worth it.
High resolution photographs of snow capped peaks in the Sputnik Planitia prompted interest from researchers in determining the atmospheric processes that could lead to methane or nitrogen snow on Pluto. Little is known about weather patterns on Pluto, including whether or not the entire atmosphere collapses and remerges during its 248 year orbit. A 2020 study identified atmospheric processes that could lead to methane snow, but estimated that only a few milimeters would accumulate every century. The authors suggested that Pluto’s climate may have led to methane snowpacks several meters deep, but free refills for any potential Plutonian skier seems unlikely.
After considering several different planets, moons, and a dwarf planet, as well as several different types of snow, one thing is clear. The Earth is a truly exceptional place, and we can confidently say it is home to the best skiing in the solar system. Amazingly beautiful mountain ranges on every single continent, energetic, chaotic weather systems that can transport billions of tons of water thousands of miles from oceans to mountain tops, and of course, a climate that has supported the development of some funny looking mammals that figured out sliding around in the snow is pretty fun. Our brief survey of mountain ranges and weather patterns that can be found elsewhere in the solar system has shown that Earth is a place like no other. There may be taller mountains, stronger winds, stranger types of snow, but nowhere else in the solar system exists the right conditions to produce anything like the skiing we know and love on Earth.
Happy Earth Day!
